Background Intra-class correlation coefficients (ICCs) provide a statistical means of testing the reliability. However, their interpretation is not well documented in the orthopedic field. The purpose of this study was to investigate the use of ICCs in the orthopedic literature and to demonstrate pitfalls regarding their use. Methods First, orthopedic articles that used ICCs were retrieved from the Pubmed database, and journal demography, ICC models and concurrent statistics used were evaluated. Second, reliability test was performed on three common physical examinations in cerebral palsy, namely, the Thomas test, the Staheli test, and popliteal angle measurement. Thirty patients were assessed by three orthopedic surgeons to explore the statistical methods testing reliability. Third, the factors affecting the ICC values were examined by simulating the data sets based on the physical examination data where the ranges, slopes, and interobserver variability were modified. Results Of the 92 orthopedic articles identified, 58 articles (63%) did not clarify the ICC model used, and only 5 articles (5%) described all models, types, and measures. In reliability testing, although the popliteal angle showed a larger mean absolute difference than the Thomas test and the Staheli test, the ICC of popliteal angle was higher, which was believed to be contrary to the context of measurement. In addition, the ICC values were affected by the model, type, and measures used. In simulated data sets, the ICC showed higher values when the range of data sets were larger, the slopes of the data sets were parallel, and the interobserver variability was smaller. Conclusions Care should be taken when interpreting the absolute ICC values, i.e., a higher ICC does not necessarily mean less variability because the ICC values can also be affected by various factors. The authors recommend that researchers clarify ICC models used and ICC values are interpreted in the context of measurement.

A growing body of evidence suggests that the costs and benefits involved in cleaning interactions can vary over space and time depending on the environmental conditions. However, whether the same cleaners actually induce variable net outcomes in terms of host fitness remains unclear to date. Branchiobdellid annelids are generally regarded as commensals or rarely parasites of their freshwater crayfish hosts, but a recent study suggests that they may also function as cleaning organisms. Under natural conditions, crayfish can experience fouling of the exposed surfaces of their exoskeletons and their gills (e.g., epibiosis) by various epibionts and particles of organic debris, and branchiobdellids graze on these sources of fouling. Here, we examined the extent to which variation in fouling pressure in the environment alters the outcome of the interaction between branchiobdellids and their crayfish host Cambaroide similis. A series of manipulations were performed in artificial environments designed to simulate either high or low fouling pressure. We used crayfish growth rates and mortality as direct measurements of the net costs and benefits of cleaning. Branchiobdellids had no significant effect on crayfish growth or mortality when cultured under low fouling pressure. However, their presence had a significant positive impact on host growth rates when cultured under high fouling pressure. These results suggest that the relationship between crayfish and branchiobdellids can fluctuate between commensalism and mutualism depending mainly on the environmental fouling pressure. We hypothesize that the outcome of cleaning interactions may largely depend on the factors directly related to the need for cleaning, such as parasite loads or fouling pressure.

BackgroundThis study was undertaken to investigate the trends of orthopedic publications during the last decade, and to document the country of origin, journal, funding source, and language of contribution using PubMed.MethodsOrthopedic articles published between 2000 and 2009 were retrieved from PubMed using the following search terms: "orthopaedic[Affiliation] AND ("2000/1/1"[PDAT]: "2009/12/31"[PDAT])" and "orthopedic[Affiliation] AND ("2000/1/1"[PDAT]: "2009/12/31"[PDAT])." The articles were downloaded in XML file format, which contained the following information: article title, author names, journal names, publication dates, article types, languages, authors' affiliations and funding sources. These information was extracted, sorted, and rearranged using the database's management software. We investigated the annual number of published orthopedic articles worldwide and the annual rate of increase. Furthermore, the country of publication origin, journal, funding source, and language of contribution were also investigated.ResultsA total of 46,322 orthopedic articles were published and registered in PubMed in the last 10 years. The worldwide number of published orthopedic articles increased from 2,889 in 2000 to 6,909 in 2009, showing an annual increase of 384.6 articles, or an annualized compound rate of 10.2%. The United States ranked highest in the number of published orthopedic articles, followed by Japan, the United Kingdom, Germany, and the Republic of Korea. Among the orthopedic articles published worldwide during the last 10 years, 37.9% pertained studies performed in the United States. Fifty-seven point three percent (57.3%) of articles were published in journals established in the United States. Among the published orthopaedic articles, 4,747 articles (10.2%) disclosed financial support by research funds, of which 4,688 (98.8%) articles utilized research funds from the United States. Most articles were published in English (97.2%, 45,030 articles).ConclusionsThe number of published orthopedic articles has been increasing over the last decade. The number of orthopedic articles, journals publication, and funding sources were dominated by research conducted in the United States, while share and growth of Asian countries including Japan, the Republic of Korea, and China were notable.

Fifth metatarsal stress fractures were found to be associated with elevated T-MT1 angle and CP angle representing a cavus foot and the increased curvature of fifth metatarsal. In addition, the extent of fifth metatarsal curvature on a 30-degree medial oblique view was found to be more related to the risk of fracture than on the AP view.